I don't know if it's just me, but I'm having problems with triddler X and O.

I haven't done a triddler for some time and started a new one.I placed a few triangles in the triddler and then marked some clues off with O's and saved it. Then I went back to the saved triddler to continue, and the O's were gone!I tried this a few times and each time, I open the saved triddler, the clues had their O's and X's gone.I also tried X and O in the picture area, and these were saved, only the X and O's in the clue area disappeared.

You do nothing wrong. What you describe is the right way the X's and O's work. Back then, when the X's and O's were added we explained why it works differently. I honestly don't remember the reason. I think it was either a matter of programming or the applet's resource.

I find large Triddlers rather problematic to solve without the X/Os available to mark off used clues -- can we please get this feature working CORRECTLY? In other words, leave the X/Os where we put them when we save our puzzles?

Having them disappear makes them useless -- they might as well not be there at all.